The principles of a venturi apparatus are well known in the art. Fluid flowing in a tube that passes through a constricted region experiences both an increase in velocity and simultaneous drop in pressure. The placement of an opening along the area of constriction produces a suction effect due to the decreased pressure of the fluid flowing in that portion of the tube. This principle has been exploited for numerous applications, including flow measurement and the introduction of additional fluids into an existing stream.
As recognized in the prior art, a simple venturi apparatus may be employed to facilitate aeration of a liquid such as wine. One such prior art design consists of a vertically oriented venturi device having a first funnel section connected to a cylindrical section that is in turn connected to a second funnel-type frusto-conical section. Two sidearm passageways extend horizontally from the cylindrical section. Liquid poured into the first funnel section is channeled into the cylindrical section, where it increases in velocity and decreases in pressure. This creates a suction effect that draws in air through the sidearm passageways. The air is thus incorporated into the liquid, which exits the device through the second funnel-type frusto-conical section. (See U.S. Patent Application Publication No. US2007/0187848A1 ('848)).
Another prior art design also utilizes the venturi principle for simultaneously pouring liquid for a container and mixing air into the liquid. Thus, the pourer of U.S. Pat. No. 6,568,660 B1 may be used for simultaneously pouring wine from a bottle and decanting the wine.
However, problems exist in both prior art designs. Notably, the devices are prone to leaking liquid out through air passageways. This is especially likely to occur when a large amount of liquid is poured through the devices. In order to minimize the likelihood of leakage, a user must maintain the device described in the '848 publication in a near perfect vertical orientation during usage, and in a carefully determined angle from vertical in the case of the pourer of the '660 patent. And even so, this may not ensure that leakage does not occur, especially when larger quantities of liquid are poured.
The prior art device is thus unpredictably prone to leakage of liquid, which can cause many additional problems for the user. A leaked beverage, particularly as with red wine, can result in stains that are difficult to clean. Such leakage also renders the device itself slippery and difficult to handle, in addition to soiling the user's hand. Moreover, beverages such as fine wine can be quite expensive, and any loss due to leakage constitutes a cost that must be borne by the user.
The '848 prior art device is also prone to formation of a vortex in the liquid. Vortical flow causes the liquid to flow along the walls of the cylindrical section and thereby tends to block the movement of air into the liquid. This blockage thereby reduces the efficiency with which the device can aerate a liquid. In the '660 prior art device, only one air passageway is provided at an inefficiently designed constriction for producing the venturi effect. The result is a very slow pouring device and poor aereation.